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A catalog of bright calibrator stars for 200-m baseline near-infrared stellar interferometry
We present in this paper a catalog of reference stars suitable forcalibrating infrared interferometric observations. In the K band,visibilities can be calibrated with a precision of 1% on baselines up to200 meters for the whole sky, and up to 300 meters for some part of thesky. This work, extending to longer baselines a previous catalogcompiled by Bordé et al. (2002, A&A, 393, 183), isparticularl y well adapted to hectometric-class interferometers such asthe Very Large Telescope Interferometer (VLTI, Glindemann et al. 2003,Proc. SPIE, 4838, 89) or the CHARA array (ten Brummelaar et al. 2003,Proc. SPIE, 4838, 69) when one is observing well-resolved, high-surfacebrightness objects (K 8). We use the absolute spectro-photometriccalibration method introduced by Cohen et al. (1999, AJ, 117, 1864) toderive the angular diameters of our new set of 948 G8-M0 calibratorstars extracted from the IRAS, 2MASS and MSX catalogs. Angular stellardiameters range from 0.6 mas to 1.8 mas (median is 1.1 mas) with amedian precision of 1.35%. For both the northern and southernhemispheres, the closest calibrator star is always less than 10°away.
| CHARM2: An updated Catalog of High Angular Resolution Measurements
We present an update of the Catalog of High Angular ResolutionMeasurements (CHARM, Richichi & Percheron \cite{CHARM}, A&A,386, 492), which includes results available until July 2004. CHARM2 is acompilation of direct measurements by high angular resolution methods,as well as indirect estimates of stellar diameters. Its main goal is toprovide a reference list of sources which can be used for calibrationand verification observations with long-baseline optical and near-IRinterferometers. Single and binary stars are included, as are complexobjects from circumstellar shells to extragalactic sources. The presentupdate provides an increase of almost a factor of two over the previousedition. Additionally, it includes several corrections and improvements,as well as a cross-check with the valuable public release observationsof the ESO Very Large Telescope Interferometer (VLTI). A total of 8231entries for 3238 unique sources are now present in CHARM2. Thisrepresents an increase of a factor of 3.4 and 2.0, respectively, overthe contents of the previous version of CHARM.The catalog is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/431/773
| TU Cassiopeiae periods and amplitudes
Light-curve observations of the double-mode Cepheid TU Cas obtained by10 different groups of observers on several photometric systems over atime span of 67 years have been carefully studied to determine thefundamental and first-overtone periods and their amplitudes on the Vmagnitude scale. The presence of a second-overtone radial pulsation isdiscussed, and it is concluded that a previous detection of this modewas spurious because of the lack of a proper zero-point correction fortwo groups of observations. It is possible that the amplitude of one ofthe two modes varies during the entire observing period, with thefundamental-mode amplitude constant at 0.69 plus or minus 0.03 and theovertone amplitude decreasing from 0.4 to 0.25 mag. If this Cepheiddisplays the two pulsation modes because it is mode switching, thisswitching time scale may be less than a few hundred years.
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| Takýmyýldýz: | Anka |
| Sað Açýklýk: | 00h34m25.15s |
| Yükselim: | -45°25'33.0" |
| Görünürdeki Parlaklýk: | 6.8 |
| Uzaklýk: | 175.131 parsek |
| özdevim Sað Açýklýk: | 11.6 |
| özdevim Yükselim: | 15.5 |
| B-T magnitude: | 8.501 |
| V-T magnitude: | 6.941 |
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